. >> reporter: president obama and mitt romney will face off in their first presidential debate tonight. >> governor romney and president obama will meet behind me. >> reporter: what happens on this stage could be pivotal with only five weeks until election day. the first debate will focus on the economy and domestic policy. both took a break tuesday, with mitt romney grabbing a bite to eat in denver, president obama visited the hoover dam for the first time. >> the president: it is spectacular. >> reporter: both relied heavily on their running mates to lead their campaign. >> how they can justify raising taxes on the middle class that has been buried the last four years. >> reporter: it didn't take long for republican vice presidential hopeful ryan to pounce on that comment. >> vice president biden just today said that the middle class over the last four years has been "buried." we agree. >> reporter: the latest poll shows the race for president is still close. which means every word and gesture tonight could impact the election. after a couple of coin tosses last night we learned pres